1. Field of the Invention
The present invention concerns benzoyl peroxide and quaternary ammonium based pharmaceutical and cosmetic compositions and their use, particularly in the treatment of acne.
2. Description of the Prior Aart
The etiopathology of acne is not well understood but acne is known to start with formation of a characteristic lesion: the comedo. This arises from obstruction of the pilosebaceous canal following dyskeratinization of the infundibular zone of the canal. A major effect of the obstruction is hyperproliferation of the resident cutaneous strains which precipitates an inflammation reaction in the organism.
Benzoyl peroxide is a known therapeutic agent for treatment of acne and has been known for several years to be a particularly interesting keratolytic agent. Amongst other qualities, it has good bacteriostatic properties.
Conventional antibiotics are also very widely used in treating acne. They possess significant bacteriostatic and anti-inflammatory properties. Oral active antibiotics are plentiful and some, for example clindamycin and especially erythromycin, may be used topically.
Benzoyl peroxide has been combined with antibiotics to improve the efficacy of anti-acne compositons. In particular, benzoyl peroxide has been combined with erythromycin (FR-A-2 378 523).
Whether or not combined with benzoyl peroxide, however, antibiotics suffer from a major drawback with prolonged use in that they render the bacterial flora resistant. They thus become relatively inactive during subsequent treatment (J. J. LEYDEN, J. Am. Acad. Dermatol. 8, (1), 41-45 (1983)).
In addition, combinations of benzoyl peroxide and erythromycin have proved to be unstable when stored.
Replacement of the antibiotics by quaternary ammonium salts has been suggested for topical treatment of acne (M. GLOOR, Arch. Dermatol. Res. 265, 207-212 (1979)). Some quaternary ammonium salts are just as effective as antibiotics against the principal strains causing acne without inducing resistance.
Stable detergent compositions for cleansing the skin have also been described. These may contain both a surfactant quaternary ammonium compound such as benzalkonium, cetalkonium, cetylpyridinium or benzethonium chloride, or cethexonium bromide, plus benzoyl peroxide (U.S. Pat. No. 3,852,210).
The combination of benzoyl peroxide with any of the quaternary ammonium salts cited in the above patent has been found to degrade after a few hours at room temperature, however.
It has now been discovered, surprisingly, that stable compositions for the treatment of acne, cutaneous ulcers and the general treatment of dermatioses and cutaneous disorders can be obtained by combining benzoyl peroxide with certain quaternary ammonium derivatives.
Benzoyl peroxide can be used in small amounts in such inventive combinations because of the latter's high stability, with an advantageous improvement in cutaneous tolerance.
Compositions according to the invention are tolerated well by the system. They possess very good antibacterial properties without inducing strain resistance, they are keratolytic, bacteriostatic (particularly with respect to one of the main acne-causing germs, propionibacterium Acnes) and effective in the treatment of and reducing the number of comedos.
Because of their properties, compositions according to the invention may be used to treat cutaneous disorders and dermatoses, particularly acne and cutaneous ulcers.
An object of the present invention is, therefore, the provision of a topical pharmaceutical and/or cosmetic composition containing benzoyl peroxide and at least one quaternary ammonium salt such as, for example, those described below.
Another object of the invention is a cosmetic treatment method using such a composition.